Re: XFS and Power Failures

[Volkan YAZICI <yazicivo@ttmail.com>]

On Thu, 21 Oct 2010, "Boyd Stephen Smith Jr." <bss@iguanasuicide.net> writes:
> XFS is the not only file system where power failure can result in a
> truncated file. Even ext3 can have that issue, though it is less
> likely.
>
> However, if the application follows a certain procedure when
> re-writing files, it will not lose data on any of these file systems.
> I suggest that Opera should be fixed to use that procedure. IIRC, this
> is a slight variation on the old "two-phase save" that some editors
> have used for decades, it simply requires a fsync on the temporary
> file.
>
> BTW, a kill -9 is very different from a power failure or a hard reset.
> In the first case, the application is allowed to do it's own cleanup;
> the kernel still cleans up after the process -- closing handles to
> kernel resources, like file descriptors; and queued tasks, like
> delayed allocation and flushing data to disk, can be run at a later
> time still. In the later, horrible things happen (e.g. in some systems
> the HDs and BUS can run for just long enough to complete a DMA
> transfer AFTER the RAM has lost coherency) and no software gets to run
> long enough to even detect what is happening, much less put the
> hardware in a known good state.

I didn't experience anything similar with reiserfs. (I'm not implying
anything, neither defensing reiserfs; just sharing my experience.)


Regards.